1. Field of the Invention
The present invention generally relates to analyzing model creating apparatuses and methods and computer-readable storage media, and more particularly to an analyzing model creating apparatus and an analyzing model creating method which create a Finite Element Method (FEM) model suited for evaluating a part bonding strength of a part that is mounted on a Printed Circuit Board (PCB), and to a computer-readable storage medium which stores a program for causing a computer to realize functions of such an analyzing model creating apparatus.
2. Description of the Related Art
Recently, due to the reduced weight and size of portable electronic equipments, it is becoming increasingly important from the point of design to secure the part bonding strength of the part that is mounted on the PCB which is assembled within the portable electronic equipment. There are proposals to improve the efficiency with which the portable electronic equipments are developed, by evaluating a virtual part bonding strength by a numerical simulation using the Finite Element Method (FEM).
Because the parts mounted on the PCB of the portable electronic equipment are extremely small, an evaluation method which directly evaluates a solder bonding part by forming a detailed mesh model of the parts is unsuited in this case. For this reason, an evaluation method which is generally employed fixes rectangular part meshes of a simple part model on PCB meshes in a joining contact state, and evaluates a PCB stress or distortion in a periphery of the part in order to indirectly evaluate the load on the part. More particularly, the part and the board are respectively divided into meshes from a three-dimensional model of the PCB, and a node located on a part mounting surface is fixed to a mesh surface of the board using a joining type contact definition, in order to create a FEM model.
Three-dimensional models of the PCB are proposed in Japanese Laid-Open Patent Applications No. 2005-115859 and No. 2006-91939, for example.
Conventionally, most of the three-dimensional models of the mounting parts have a simple block shape, and it is relatively easy to create the meshes. However, because the number of meshes is large, there was a problem in that a large number of processes are required to create the meshes.
On the other hand, the division of the board into the meshes and the division of the evaluation target part into the meshes are performed independently, and the meshes of the board and the meshes of the evaluation target part are fixed using the joining type contact definition. For this reason, the size and direction (or orientation) of an evaluation target element 12 may differ depending on the position in the periphery of the evaluation target part as shown in FIG. 1. Consequently, a relative error of approximately 30%, for example, is generated in the evaluation result depending on the manner in which the PCB model is created. FIG. 1 is a diagram for explaining the conventional FEM model. In FIG. 1, (a) shows a plan view of the FEM model, and (b) shows a portion of the evaluation target part of the FEM model. In FIG. 1, a reference numeral 10 denotes a mesh model of the board, and a reference numeral 11 denotes a mesh model of the evaluation target part.